Pedal device for automobile and damper for use in the same

ABSTRACT

A pedal device ( 1 ) for an automobile includes a supporting frame ( 2 ); an accelerator pedal arm ( 3 ) made of a rigid metal and supported by the supporting frame ( 2 ) in such a manner as to be rotatable about an axis A in directions R; a spring means ( 4 ) for rotatively urging the accelerator pedal arm ( 3 ) toward an initial position of its rotation; a damper ( 5 ) for imparting a resistance force to the rotation in the directions R of the accelerator pedal arm ( 3 ); and a stopper for stopping the rotation of the accelerator pedal arm ( 3 ) at the initial position of its rotation.

TECHNICAL FIELD

The present invention relates to a pedal device having a damper forimparting an appropriate brake to an accelerator pedal arm, a brakepedal arm, a clutch pedal arm, or the like of an automobile and a dampersuitable for use in the pedal device.

BACKGROUND ART

Fine control of fuel injection in automotive engines is required for thepurposes of low fuel consumption of automobiles and reduction of carbondioxide, and electronic regulation of the throttle valve opening basedon the pressing down of an accelerator pedal has been put to practicaluse.

In automobiles in which fuel injection of the engine is effected byelectronic control, an accelerator cable disposed between an acceleratorpedal arm and a throttle valve is normally omitted. With theseautomobiles without the accelerator cables, the feeling of reactionforce with respect to the pedal pressing force differs in comparisonwith the accelerator cables. Moreover, the hysteresis characteristic inthe relationship between the pressing force in the pedal pressingdirection and the holding force in the pedal returning direction forms asubstantially narrow loop, i.e., the pedal-pressing-force characteristicwith respect to the amount of the pedal pressed becomes linear.Therefore, if a general driver who is accustomed to driving anautomobile with the accelerator cable drives the automobile without theaccelerator cable, there arises a problem in that, for instance, fatiguecan occur early when shocks of the acceleration or deceleration of theautomobile occur due to the movement of the accelerator pedal duringrunning on a rough terrain, or when the driver tries to fixedly hold theaccelerator pedal for a long time during such as high-speed running.

To prevent excessive pressing down by obtaining a large reaction forcewith respect to the pedal pressing force, if the spring force of areturn spring for returning the pedal arm to the initial position ofrotation is simply made large, there is a possibility of causing earlyfatigue to the pedal-pressing foot due to the large reaction force fromthe return spring during constant-speed running.

Accordingly, a damper has been proposed which imparts a resistance forcebased on linearly increasing friction between a rotating member rotatedby the rotation of the pedal arm and a movable member coming intocontact with this rotating member. According to this damper, it ispossible to obtain favorable effects such as that the damper has such ahysteresis characteristic that the range of the pedal pressing forceallowing the amount of the pedal pressed to be maintained at a fixedlevel in correspondence with the amount of the pedal pressed can be madelarge, that the damper can be installed compactly, that the adjustmentof the reaction force can be effected very simply, and that a change inits characteristics can be reduced. However, since the hysteresischaracteristic is obtained on the basis of dynamic friction and staticfriction, large resistance based on static friction before leading todynamic friction is applied to the pedal arm as a reaction force at thestart of the pressing down of the pedal from the initial position ofrotation of the pedal arm. Consequently, the driver of the automobilewho operates the pedal arm receives from the pedal the unpleasantsensation of, as it were, pressing the foot against an immovable wall inthe early stage of pressing down, and thus experiences a feeling offatigue in the pedal operation.

The above-described problem occurs not only with the accelerator pedalarm, but can also occur with, for example, the brake pedal arm, theclutch pedal arm, and the foot-operated parking brake arm.

The present invention has been devised in view of the above-describedaspects, and its object is to provide a pedal device for an automobilewhich excels in the operational feeling, does not cause the driver toexperiences a feeling of fatigue in the pedal operation, and makes itpossible to enlarge the range of the pedal pressing force allowing theamount of the pedal pressed to be maintained at a fixed level incorrespondence with the amount of the pedal pressed, as well as a dampersuitable for use in the pedal device.

DISCLOSURE OF INVENTION

A pedal device for an automobile in accordance with a first aspect ofthe invention comprises a damper for imparting a resistance force to therotation of a pedal arm, the damper including a movable member which isdisposed movably in an axial direction but immovable in a directionabout the axis, a rotating member disposed rotatably about the axis andfacing the movable member, spring means for resiliently urging themovable member toward the rotating member, andfrictional-resistance-force generating means for producing a frictionalresistance force as the resistance force in the rotation of the rotatingmember, and for increasing the frictional resistance force by increasingthe spring force of the spring means by causing the movable member tomove away from the rotating member in the axial direction against theresiliency of the spring means, wherein a torque which graduallyincreases from an initial position of rotation of the pedal arm to anyangle of 0.5 to 20% of a full angle of rotation thereof is imparted tothe rotating member to permit the rotation of the pedal arm, and therotating member is subsequently rotated in conjunction with the rotationof the pedal arm.

In accordance with the pedal device according to the first aspect, atorque which gradually increases from the initial position of rotationto any angle of 0.5 to 20% of the full angle of rotation is imparted tothe rotating member to permit the rotation of the pedal arm, and therotating member is subsequently rotated in conjunction with the rotationof the pedal arm. Accordingly, at the start of the pressing down of thepedal, the pedal arm is rotated in conjunction with it, with the resultthat it is possible to eliminate the sensation of being subjected to alarge resistance based on the static friction in thefrictional-resistance-force generating means. Hence, the driver whooperates the pedal arm is able to start the automobile naturally withoutreceiving from the pedal the unpleasant sensation of pressing the footagainst, so to speak, an immovable wall, and is able to comfortablyeffect the pedal operation without experiencing fatigue.

If the angle of rotation of the pedal arm for rotating the rotatingmember in conjunction with the rotation of the pedal arm is less than0.5% of the full angle of rotation, the driver receives a large reactionforce based on the static friction in the frictional-resistance-forcegenerating means substantially at the same time as the pressing of thepedal. This situation is substantially similar to the case in which thefoot is pressed against an immovable wall, and natural starting of theautomobile is hence impossible. On the other hand, the angle of rotationof the pedal arm exceeds 20% of the full angle of rotation, the range ofthe pedal pressing force allowing the amount of the pedal pressed to bemaintained at a fixed level in correspondence with the amount of thepedal pressed (the angle of rotation of the pedal arm) becomes small,and this effect can be obtained only at a high speed.

In addition, in accordance with the pedal device according to the firstaspect, when the rotating member is rotated by the rotation of the pedalarm due to the pressing down of the pedal, the frictional resistanceforce which increases occurs in the frictional-resistance-forcegenerating means. Therefore, by virtue of this resistance force, it ispossible to prevent fuel from being consumed more than before by, forexample, excessively pressing down on the accelerator pedal. Moreover,as the result of the fact that it is possible to enlarge the range ofthe pedal pressing force in which the angle of rotation of the pedal armcan be maintained at a fixed level in correspondence with the amount ofthe pedal pressed, the amount of the pedal pressed can be easilymaintained at a fixed level in correspondence with the speed during theconstant-speed running at various speeds ranging from the low speed tothe high speed. Hence it is possible to overcome the trouble of such ascausing early fatigue to the pedal-pressing foot.

In the pedal device for an automobile in accordance with a second aspectof the invention, in the pedal device according to the first aspect, thefrictional-resistance-force generating means has an inclined surfaceformed on one surface of the rotating member facing the movable memberand an inclined surface formed on one surface of the movable memberfacing the rotating member and adapted to be brought into planar contactwith the inclined surface.

In accordance with the pedal device according to the second aspect, byappropriately setting the coefficients of friction of both inclinedsurfaces, it is possible to approximately determine the resistance forcewhich can be applied to the rotation of the pedal arm. Further, it ispossible to effect very simply the adjustment of the reaction forcehaving a hysteresis characteristic in the relationship between theamount of the pedal pressed and the pedal pressing force.

In the pedal device for an automobile in accordance with a third aspectof the invention, in the pedal device according to the first or secondaspect, the movable member has a movable member body and a projectionformed integrally on one surface of the movable member body in such amanner as to project in the axial direction toward one surface of therotating member, the rotating member has a rotating member body and aprojection formed integrally on one surface of the rotating member bodyin such a manner as to project in the axial direction toward the onesurface of the movable member, and the frictional-resistance-forcegenerating means has inclined surfaces which are formed on bothprojections of the movable member and the rotating member and arebrought into planar contact with each other.

In the pedal device according to the third aspect, since the thefrictional-resistance-force generating means is formed by inclinedsurfaces which are formed on both projections of the movable member andthe rotating member and are brought into planar contact with each other,the pedal device can be made very compact, and can be installed bymaking effective use of a small space. Furthermore, by appropriatelysetting the coefficients of friction of the inclined surfaces which arebrought into planar contact with each other, it is possible toapproximately determine the resistance force which can be applied to therotation of the pedal arm. Further, it is possible to effect very simplythe adjustment of the reaction force having a hysteresis characteristicin the relationship between the amount of the pedal pressed and thepedal pressing force.

In the pedal device for an automobile in accordance with a fourth aspectof the invention, in the pedal device according to any one of theabove-described aspects, the rotation of the pedal arm is adapted to betransmitted to the rotating member via a rotatable shaft, the damperfurther includes a hollow cylindrical member in which the movable memberand the rotating member are accommodated and a cover disposed at one endsurface of the hollow cylindrical member in such a manner as to beimmovable in the direction about the axis, the rotating member is incontact with the cover in such a manner as to be slidable in thedirection about the axis and by being urged by the spring force of thespring means, and the movable member is in contact with the hollowcylindrical member in such a manner as to be slidable in the axialdirection.

In the pedal device according to the fourth aspect, in the rotation ofthe rotating member, the frictional resistance between the rotatingmember and the cover and the frictional resistance between the movablemember and the hollow cylindrical member can be respectively added tothe frictional resistance of the frictional-resistance-force generatingmeans. Therefore, the frictional-resistance-force generating means canbe arranged more compactly.

In the pedal device for an automobile in accordance with a fifth aspectof the invention, in the pedal device according to the fourth aspect,the pedal arm and the rotatable shaft are substantially rigid members incomparison with the hollow cylindrical member, the rotating member, themovable member and the cover, and the rotation of the pedal arm from theinitial position of rotation to any angle of 0.5 to 20% of the fullangle of rotation is effected by the elastic deformation of at least oneof the hollow cylindrical member, the rotating member and the movablemember.

In accordance with the pedal device according to the fifth aspect, sincethe early rotation of the pedal arm is allowed by the elasticdeformation of at least one of the hollow cylindrical member, therotating member and the movable member, a resilient reaction force isgradually applied to the pressing foot in proportion to the amount ofpressing, so that the operational feeling during the early rotation ofthe pedal arm can be made very excellent.

In the case where the early rotation of the pedal arm is effected by theelastic deformation of the hollow cylindrical member, the rotatingmember and the movable member, by appropriately setting their moduli ofelasticity, it is possible to provide a pedal device imparting anoptimum operational feeling in the early rotation of the pedal arm.

As the materials for forming the hollow cylindrical member, the rotatingmember and the movable member for effecting the elastic deformation, thefollowing are required. First, since a rotatable shaft is normallyinserted in the rotating member, and this rotatable shaft repeatsrotational motion, the rotating member must be such as to be able towithstand its repeated stress, and breakage and permanent set in fatigue(permanent deformation) must not occur. Moreover, since the rotatingmember slides on the movable member, and on the cover in some cases, therotating member should preferably be formed of a material which excelsin wear resistance and generates a stable frictional torque. In a casewhere the rotatable shaft is directly inserted in the rotating member, afairly high strength is required for the rotating member, but byinterposing a link mechanism or the like without directly inserting therotatable shaft, it is possible to reduce the load applied to therotating member.

As for the movable member and the hollow cylindrical member, thestrength is not so much required as the rotating member, but, basicallyspeaking, the breakage and the permanent set in fatigue must not occurin the repeated rotation of the rotating member in the same way as therotating member, and the movable member and the hollow cylindricalmember should preferably be formed of materials which excel in wearresistance and generate a stable frictional torque in sliding with theirrespective mating members.

By taking these aspects into consideration, it suffices if a modulus ofelasticity in bending, E, of a material for forming the hollowcylindrical member is such that 2×10⁴ kgf/cm²≦E as in the pedal devicein accordance with a sixth aspect of the invention. In addition, thematerial for forming the hollow cylindrical member should preferably beformed of a resin as a base material as in the pedal device inaccordance with a seventh aspect of the invention. Such a resin is notparticularly restricted insofar as a required modulus of elasticity inbending is satisfied in the relationship with the movable member and therotating member and in the relationship with the pedal device accordingto the sixth aspect of the invention, and it is possible to use a resinas a simple substance or a combination of two or more kinds of resins,or a material in which various fillers are compounded with these resins.Preferably, as in the pedal device in accordance with an eighth aspectof the invention, as the resin, the material for forming the hollowcylindrical member is one kind or two or more kinds selected from apolyamide resin such as nylon 6, nylon 66, nylon 12, nylon 46 or nylonMXD6, a polyoxymethylene resin such as an acetal copolymer or an acetalhomopolymer, a thermoplastic polyester resin such as polyethyleneterephthalate or polybutylene terephthalate, a liquid crystal polyesterresin, a modified polyphenylene ether resin, a polyphenylene sulfideresin, a polyether sulfone resin, an aliphatic polyketone resin and apolyether ketone resin. Further, as in the pedal device in accordancewith a ninth aspect of the invention, the filler includes one kind ortwo or more kinds selected from graphite, fluororesin, molybdenumdisulfide, boron nitride, glass fibers, carbon fibers, aromaticpolyamide fibers and potassium titanate whiskers, as well as lead, zinc,tin and copper and alloys thereof. It should be noted that, depending ona case, the material for forming the hollow cylindrical member may be ametal which can be regarded as a substantially rigid material as in thepedal device in accordance with a 10th aspect of the invention.

The modulus of elasticity in bending, E, of a material for forming themovable member is such that 2×10⁴ kgf/cm²≦E≦20×10⁴ kgf/cm² as in thepedal device in accordance with an 11th aspect of the invention,preferably 5×10⁴ kgf/cm²≦E≦20×10⁴ kgf/cm² as in the pedal device inaccordance with a 12th aspect of the invention, more preferably 7×10⁴kgf/cm²≦E≦18×10⁴ kgf/cm² as in the pedal device in accordance with a13th aspect of the invention. The modulus of elasticity in bending, E,of a material for forming the rotating member is such that 2.5×10⁴kgf/cm²≦E≦25×10⁴ kgf/cm² as in the pedal device in accordance with a14th aspect of the invention, preferably 5×10⁴ kgf/cm²≦E≦23×10⁴ kgf/cm²as in the pedal device in accordance with a 15th aspect of theinvention, more preferably 10×10⁴ kgf/cm²≦E≦20×10⁴ kgf/cm² as in thepedal device in accordance with a 16th aspect of the invention.

It should be noted that if the modulus of elasticity in bending, E, ofthe material for forming the rotating member exceeds 25×10⁴ kgf/cm², itis necessary to make substantially small the moduli of elasticity inbending, E, of the materials for forming the movable member and thehollow cylindrical member, and there are possibilities of causingbreakage and permanent set in fatigue, thereby causing a problem indurability.

In the case where the early rotation of the pedal arm is effected by theelastic deformation of the hollow cylindrical member, the rotatingmember and the movable member, the respective materials of the movablemember and the rotating member can be appropriately selected frommaterials which satisfy the aforementioned moduli of elasticity inbending. The combination of the materials, however, may be determined bytaking into consideration the hysteresis characteristic and the slidingcharacteristic that are required.

The materials for forming the movable member and the rotating membershould preferably comprise resins in the same way as the material forforming the hollow cylindrical member, as in the pedal device inaccordance with a 17th aspect of the invention. In this case, the resinsfor forming the movable member and the rotating member are notparticularly restricted insofar as the required modulus of elasticity inbending is satisfied in the relationship with the hollow cylindricalmember. In the same way as the material for forming the hollowcylindrical member, it is possible to use a resin as a simple substanceor a combination of two or more kinds of resins, or a material in whichvarious fillers are compounded with these resins.

As in the pedal device in accordance with an 18th aspect of theinvention, as the resins, each of the materials for forming the movablemember and the rotating member preferably comprises one kind or two ormore kinds selected from a polyamide resin such as nylon 6, nylon 66,nylon 12, nylon 46 or nylon MXD6, a polyoxymethylene resin such as anacetal copolymer or an acetal homopolymer, a thermoplastic polyesterresin such as polyethylene terephthalate or polybutylene terephthalate,a liquid crystal polyester resin, a modified polyphenylene ether resin,a polyphenylene sulfide resin, a polyether sulfone resin, an aliphaticpolyketone resin and a polyether ketone resin. Further, as in the pedaldevice in accordance with a 19th aspect of the invention, the fillerwhich is compounded therewith preferably includes one kind or two ormore kinds selected from graphite, fluororesin, molybdenum disulfide,boron nitride, glass fibers, carbon fibers, aromatic polyamide fibersand potassium titanate whiskers, as well as lead, zinc, tin and copperand alloys thereof.

It should be noted that the pedal arm in the device of the invention ispreferably the aforementioned accelerator pedal arm, but, alternatively,the pedal arm is also applicable to a brake pedal arm, a clutch pedalarm, or the like.

Hereafter, a description will be given of the present invention and itsembodiment with reference to the preferred example shown in thedrawings. It should be noted that the present invention is not limitedto this embodiment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front cross-sectional view of a preferred embodiment inaccordance with the invention;

FIG. 2 is a left side view of the embodiment shown in FIG. 1;

FIG. 3 is a right side view of a damper of the embodiment shown in FIG.1;

FIG. 4 is a left side view of a movable member of the embodiment shownin FIG. 1;

FIG. 5 is a cross-sectional view, taken along line IV—IV of FIG. 4, ofthe movable member shown in FIG. 4;

FIG. 6(a) is a right side view of the movable member of the embodimentshown in FIG. 1;

FIG. 6(b) is an explanatory diagram in which projections, recesses, andstepped portions of the movable member are illustrated in developedform;

FIG. 7(a) is a left side view of the rotating member of the embodimentshown in FIG. 1;

FIG. 7(b) is an explanatory diagram in which projections, recesses, andstepped portions of the rotating member are illustrated in developedform;

FIG. 8 is a right side view of the rotating member of the embodimentshown in FIG. 1;

FIG. 9 is a cross-sectional view, taken along line IX—IX, of therotating member of the embodiment shown in FIG. 8 and illustrating therelationship with a rotatable shaft;

FIG. 10 is a diagram of the relationship between the angle of rotationof a pedal arm of the embodiment shown in FIG. 1 and the pedal pressingforce; and

FIG. 11 is a diagram explaining the operation of the damper of theembodiment shown in FIG. 1.

EMBODIMENT

In FIGS. 1 to 9, a pedal device 1 for an automobile in accordance withan embodiment of the present invention is comprised of a supportingframe 2; a pedal arm, i.e., in this embodiment, an accelerator pedal arm3 which is made of a rigid metal and supported by the supporting frame 2in such a manner as to be rotatable about an axis A in directions R; aspring means 4 for rotatively urging the accelerator pedal arm 3 towardan initial position of its rotation; a damper 5 for imparting aresistance force to the rotation in the directions R of the acceleratorpedal arm 3; and a stopper (not shown) for stopping the rotation of theaccelerator pedal arm 3 at the initial position of its rotation.

The supporting frame 2 at its bottom plate portion 13 is fixed to avehicle body 11 by means of rivets or bolts 12 or the like, androtatably supports the rotatable shaft 14 which is made of a rigid metalat its both side walls 15 and 19.

The accelerator pedal arm 3 has an accelerator pedal (not shown) at itstip, is secured to one end portion 20 of the rotatable shaft 14, and issupported by the supporting frame 2 via the rotatable shaft 14 in such amanner as to be rotatable in the directions R.

The spring means 4 in this embodiment is formed by a coil spring,preferably a torsion coil spring 16, in particular. One end portion 17of the torsion coil spring 16 is engaged with the side wall 15 of thesupporting frame 2, while the other end portion 18 thereof is engagedwith the accelerator pedal arm 3, thereby constantly urging theaccelerator pedal arm 3 resiliently in the counterclockwise direction inthe directions R in FIG. 2. As the spring means 4, a compression springmay be used instead of the torsion coil spring 16.

The damper 5 is comprised of a hollow cylindrical member 22 with abottom fixed to the side wall 15 of the supporting frame 2 at by meansof bolts 21 or the like; a movable member 23 formed in the shape of anannular plate and accommodated in the hollow cylindrical member 22 insuch a manner as to be movable with respect to the hollow cylindricalmember 22 in the direction of its axis A but immovable in directionsabout the axis A, i.e., in the directions R; a coil spring, preferably acompression coil spring 27, in particular, serving as a spring meansdisposed between the movable member 23 and a bottom portion 25 of thehollow cylindrical member 22 and having one end 24 abutting against thebottom portion 25 of the hollow cylindrical member 22 and another end 26abutting against the movable member 23; a rotating member 28accommodated in the hollow cylindrical member 22 in such a manner as tooppose the movable member 23 serving as a movable spring receiver and tobe rotatable about the axis A in the directions R with respect to thehollow cylindrical member 22; a cover 30 disposed at one end face of thehollow cylindrical member 22 in such a manner as to be immovable indirections about the axis; and a frictional-resistance-force generatingmeans 29 which generates a frictional resistance force as theaforementioned resistance force in the rotation in the directions R ofthe rotating member 28, causes the movable member 23 to move away fromthe rotating member 28 in the axial direction against the resiliency ofthe coil spring 27 and approach the bottom portion 25 of the hollowcylindrical member 22 so as to increase the spring reaction force of thecoil spring 27, thereby increasing the frictional resistance force.

The hollow cylindrical member 22 with a bottom in this embodiment has ahollow cylindrical portion 31 and the aforementioned bottom portion 25serving as a fixed spring receiver formed integrally with the other endface of the hollow cylindrical portion 31.

The hollow cylindrical portion 31 has on its inner peripheral surface 33at least one, in this embodiment six, grooves 41 formed in such a manneras to extend in the direction of the axis A. The grooves 41 are arrangedat equiangular intervals in the direction R.

A collar portion 32 having a substantially elliptical outer shape hasthrough holes 43 and 44 at opposite end portions in its long-axisdirection. The hollow cylindrical member 22 is fixedly supported at thecollar portion 32 by the side wall 15 by means of the bolts 21 or thelike which are passed through the through holes 43 and 44.

An annular groove 46 is formed in an end face 45 of the bottom portion25, and one end 24 of the coil spring 27 is seated in the groove 46.

The hollow cylindrical member 22 in this embodiment is integrally formedof a forming material comprising a polyacetal copolymer and having amodulus of elasticity in bending E=2.6×10⁴ kgf/cm².

As shown in detail particularly in FIGS. 4, 5, and 6, the movable member23 includes a movable member body 56 formed in the shape of an annularplate and having a through hole 55 in its center; at least one, in thisembodiment six, projections 58 formed integrally on an outer peripheralsurface 57 of the movable member body 56; an annular groove 60 formed ina face 59 facing one end face 45 of the bottom portion 25; at least one,in this embodiment three, projections 86 formed integrally on an outerperipheral side of a surface 81 facing a surface 82 of a rotating memberbody 67 of the rotating member 28, in such a manner as to project in thedirection of the axis A toward the surface 82 of the rotating member 28;and recesses 91 which are respectively formed in the surface 81 in sucha manner as to be contiguous to the projections 86 and define steppedportions 92. The projections 58 are arranged at equiangular intervals inthe direction R, and are disposed in the grooves 41 in such a manner asto be movable in the direction of the axis A. As a result, the movablemember 23 is movable in the direction of the axis A but immovable in thedirections R, such that the movable member 23 at the projections 58 isin contact with the hollow cylindrical member 22 slidably in thedirection of the axis A. The projections 86 are arranged at equiangularintervals in the direction R. The other end 26 of the coil spring 27 isseated in the groove 60 of the movable member body 56.

The movable member 23 in this embodiment is integrally formed of aforming material comprising a liquid crystal polyester resin compositioncontaining a fluoroplastic and having a modulus of elasticity in bendingE=10×10⁴ kgf/cm².

The coil spring 27 is disposed in the hollow cylindrical portion 31concentrically therewith in such a manner as to be resilientlycompressed so as to cause the movable member 23 to move away from thebottom portion 25 in the direction of the axis A.

As shown in detail particularly in FIGS. 7, 8, and 9, the rotatingmember 28 has a hollow cylindrical portion 65; a rotating member body 67formed in the shape of an annular plate integrally at one end side of anouter peripheral surface 66 of the hollow cylindrical portion 65; atleast one, in this embodiment three, projections 84 formed integrally onan outer peripheral side of the annular surface 82 of the rotatingmember body 67 in such a manner as to project in the direction of theaxis A toward the surface 81 of the movable member 23; and recesses 93which are respectively formed in the surface 82 in such a manner as tobe contiguous to the projections 84 and define stepped portions 94. Oneend side of the hollow cylindrical portion 65 is disposed in a throughhole 64 of the cover 30, and is supported by an inner peripheral surfaceof the cover 30, which defines the through hole 64, in such a manner asto be rotatable in the directions R. The other end side of the hollowcylindrical portion 65 is passed through the through hole 55, andextends in such a manner as to contact an inner peripheral surface 68 ofthe movable member body 56, which defines the through hole 55, so as tobe relatively slidable with respect to the inner peripheral surface 68of the movable member body 56 in the direction of the axis A and in thedirections R. The other end portion 70 of the rotatable shaft 14 isfixedly inserted and fitted in a central hole 69 of the hollowcylindrical portion 65, and the projections 84 are arranged atequiangular intervals in the direction R.

It should be noted that if the hollow cylindrical portion 65 is formedin an elongated form so as to be passed through the through hole 55, therotation of the rotating member 28 can be favorably guided by the innerperipheral surface 68 of the movable member body 56. An arrangement maybe alternatively provided such that the hollow cylindrical portion 65 isformed in a short form without extending into the through hole 55, andthe rotation of the rotating member 28 is guided by the inner peripheralsurface of the cover 30 which defines the through hole 64.

The rotating member 28 in this embodiment is integrally formed of aforming material comprising a nylon MXD6/polyphenylene ether resincomposition containing glass fibers and having a modulus of elasticityin bending E=18×10⁴ kgf/cm².

The cover 30 having the through hole 64, through which the rotatableshaft 14 is passed, is threadedly engaged with a threaded portion formedon the inner peripheral surface 33 of the hollow cylindrical portion 31,and is thus fixed to one end face of the hollow cylindrical portion 31in such a manner as to be immovable in the directions about the axis A.An annular surface 87 of the rotating member body 67 is in contact witha fixed surface 88 which is one surface of the cover 30, in such amanner as to be slidable in the directions about the axis A and by beingurged by the spring force of the coil spring 27. It should be noted thatif the state in which the cover 30 is threadedly fitted into the hollowcylindrical portion 31 is changed, the initial state of compression ofthe coil spring 27 can be changed, thereby making it possible toarbitrarily adjust and set the initial resistance force and make itpossible to obtain an optimum initial resistance force.

The cover 30 in this embodiment is integrally formed of a formingmaterial comprising a polyacetal copolymer resin composition containingcarbon fibers and having a modulus of elasticity in bending E=16×10⁴kgf/cm².

The frictional-resistance-force generating means 29 includes theinclined surfaces 83 formed respectively on the projections 84; inclinedsurfaces 85 formed respectively on the projections 86 so as to bebrought into planar contact with the inclined surfaces 83; the annularsurface 87 of the rotating member body 67; the fixed surface 88 of thecover 30 for coming into planar contact with the rotatable surface 87;and the mutually sliding surfaces of the hollow cylindrical member body31 and the projections 58 in the groove 41.

The inclined surfaces 83 and 85 are formed complementarily in such amanner as to come into planar contact with each other, preferably insuch a manner as to be inclined about 45° with respect to the axis A.

Distal ends in the direction of the axis A of the respective projections84 are fitted into the recesses 91, while distal ends in the directionof the axis A of the respective projections 86 are fitted into therecesses 93. Further, the position of initial planar contact between theinclined surface 83 and the inclined surface 85 is defined by thestepped portion 92 and the stepped portion 94.

The accelerator pedal arm 3 and the rotatable shaft 14 are formed ofmetal materials which are substantially rigid members in comparison withthe hollow cylindrical member 22, the rotating member 28, the movablemember 23, and the cover 30.

In a vehicle, e.g., an automobile, having the above-described pedaldevice 1, if the accelerator pedal is pressed down, which in turn causesthe accelerator pedal arm 3 to be rotated clockwise in the direction Rin FIG. 2 against the resiliency of the coil spring 16, fuel injectionfor the engine is increased by the unillustrated electronic controllerincluding a detector for detecting the angle of rotation of theaccelerator pedal arm 3, thereby accelerating the automobile. On theother hand, if the pressing of the accelerator pedal is canceled, whichin turn causes the accelerator pedal arm 3 to be rotatedcounterclockwise in the direction R in FIG. 2 by the resiliency of thecoil spring 16, fuel injection for the engine is decreased by theunillustrated electronic controller, thereby decelerating theautomobile.

With the pedal device 1, as shown in FIG. 10, when the accelerator pedalis pressed down, and until the accelerator pedal arm 3 is rotated fromthe initial position of rotation, 0°, to any angle θb° between 0.5 to20% of a full angle of rotation θMax°, the rotation of the acceleratorpedal arm 3 allows the elastic deformation of the hollow cylindricalmember 22, the rotating member 28, and the movable member 23 to occurpreferentially without practically causing the rotation of the rotatingmember 28. When the accelerator pedal arm 3 is rotated beyond the angleθb°, the rotation in the direction R is caused in the rotating member 28in correspondence with the rotation of the accelerator pedal arm 3.Namely, with the pedal device 1, the arrangement provided is such that atorque (pedal pressing force) T which gradually increases from theinitial position of rotation, 0°, to the angle θb° of the acceleratorpedal arm 3 is imparted to the rotating member 28 to permit the rotationof the accelerator pedal arm 3, as shown by the line a-b, and therotating member 28 is subsequently rotated in the direction R inconjunction with the rotation of the accelerator pedal arm 3.

If the rotating member 28 is rotated in the direction R, the projections84 are also rotated in the direction R, and the movable member 23, whichis integrally provided with the projections 86 with their inclinedsurfaces 85 brought into planar contact with the inclined surfaces 83,is moved toward the bottom portion 25 against the resiliency of the coilspring 27 in the direction of the axis A owing to the rotation in thedirection R of the projections 84, as shown in FIG. 11. On the otherhand, if the pressing of the pedal is canceled at an angle of, e.g.,θef°, the accelerator pedal arm 3 is returned to its original position0° by the resiliency of the coil spring 16, and the movable member 23 issimilarly returned to its original position, as shown in FIG. 1.

In accordance with the above-described pedal device 1, the acceleratorpedal arm 3 can be rotated from the initial position of rotation, 0°, tothe angle θb° mainly by the elastic deformation of the hollowcylindrical member 22, the rotating member 28 and the movable member 23,and the rotating member 28 is subsequently rotated in conjunction withthe rotation of the accelerator pedal arm 3. Therefore, at the start ofthe pressing down of the pedal, the accelerator pedal arm 3 is rotatedin conjunction with it, with the result that it is possible to eliminatethe sensation of being subjected to a large resistance based on thestatic friction in the frictional-resistance-force generating means 29.Hence, the driver of the automobile who operates the accelerator pedalarm 3 does not receive from the accelerator pedal the unpleasantsensation of pressing the foot against, so to speak, an immovable wall,i.e., the sensation due to the reaction force as shown by the line a-gin FIG. 10, and is able to comfortably effect the pedal operationwithout experiencing fatigue.

Furthermore, with the pedal device 1, if the pedal is pressed down inexcess of the angle θb°, an appropriate gradually increasing resistanceforce (reaction force) is imparted to the rotation of the acceleratorpedal arm 3 based on the pressing down of the pedal, as shown by theline b-c in FIG. 10, due to the frictional resistance between theinclined surfaces 83 and the inclined surfaces 85 which are pressedagainst each other by the gradually increasing resiliency of the coilspring 27, the frictional resistance between the surface 87 and thefixed surface 88, and the frictional resistance between the hollowcylindrical member 31 and the projections 58 in the groove 41. Thus, itis possible to prevent fuel from being consumed more than is necessaryby excessively pressing down on the accelerator pedal. On the otherhand, if the pressing of the pedal is canceled at the angle θef°, thefrictional resistance between the inclined surfaces 83 and the inclinedsurfaces 85, the frictional resistance between the surface 87 and thefixed surface 88, and the frictional resistance between the hollowcylindrical member 31 and the projections 58 in the groove 41 becomeextremely small, so that the accelerator pedal arm 3 is rotated andreturned speedily to its original position with a small resistance forcedue to the resiliency of the coil spring 16.

In addition, with the pedal device 1, in a case where after the pressingof the pedal, the pressing of the pedal is maintained at, for example,the angle θef° corresponding to the case of the constant-speed running,even if the pedal pressing force is reduced from Te to Tf, the angle ofrotation θef° of the accelerator pedal arm 3 can be maintained by virtueof the hysteresis characteristic a-b-e-f between the angle of rotationof the pedal arm and the pedal pressing force, which is based on thefrictional resistance between the inclined surfaces 83 and the inclinedsurfaces 85, the frictional resistance between the surface 87 and thefixed surface 88, and the frictional resistance between the hollowcylindrical member 31 and the projections 58 in the groove 41.Therefore, it is possible to overcome the trouble of such as causingearly fatigue to the pedal-pressing foot. Namely, with the pedal device1, as the result of the fact that it is possible to enlarge the rangeTe-Tf of the pedal pressing force T in which the angle of rotation θef°of the accelerator pedal arm 3 with a given amount of the pedal pressedcan be maintained at a fixed level in correspondence with the amount ofthe pedal pressed, the amount of the pedal pressed can be easilymaintained at a fixed level in correspondence with the speed during theconstant-speed running at various speeds ranging from the low speed tothe high speed. Hence it is possible to overcome the trouble of such ascausing early fatigue to the pedal-pressing foot.

Furthermore, with the pedal device 1, since it is possible toapproximately determine the resistance force which can be imparted tothe rotation of the accelerator pedal arm 3 by the frictional resistancebetween the inclined surfaces 83 and the inclined surfaces 85, thefrictional resistance between the surface 87 and the fixed surface 88,and the frictional resistance between the hollow cylindrical member 31and the projections 58 in the groove 41, it is possible to effect verysimply the adjustment of the reaction force having a hysteresischaracteristic. Further, by appropriately setting the respective values,the device can be made very compact, and can be installed by makingeffective use of a small space.

In addition, with the pedal device 1, since the coil spring 27practically does not cause the returning force for returning theaccelerator pedal arm 3 to its initial position, the reaction force issubstantially not produced to the accelerator pedal arm 3 duringconstant-speed running, so that there is a further advantage in thatearly fatigue is not caused to the pedal-pressing foot.

Moreover, with the pedal device 1, since the coil spring 27 is disposedbetween the movable member 23 and the bottom portion 25 of the hollowcylindrical member 22 which do not rotate relative to each other, thecoil spring 27 is not twisted by the rotation of the rotating member 28.Hence, the trouble of such as malfunctioning due to the twisting of thecoil spring 27 does not occur.

With the pedal device 1 in accordance with this embodiment, when a testwas conducted by repeating 3,000,000 times the rotation of theaccelerator pedal arm 3 from the initial position of rotation, 0°, tothe maximum angle θmax° (full stroke) (corresponding to the loop of thelines a-b-c-d in FIG. 10), no breakage, permanent set in fatigue, andthe like occurred in each of the hollow cylindrical member 22, themovable member 23, the rotating member 28, and the cover 30, the angleof rotation θb° was in the range of 0.5 to 20% of θmax°, and the rangeTe-Tf of the pedal pressing force in which the angle of rotation θef°during constant-speed running can be maintained at a fixed level was ina satisfactory range.

In accordance with the invention, it is possible to provide a pedaldevice for an automobile which excels in the operational feeling, doesnot cause the driver to experiences a feeling of fatigue in the pedaloperation, and makes it possible to enlarge the range of the pedalpressing force allowing the amount of the pedal pressed to be maintainedat a fixed level in correspondence with the amount of the pedal pressed,as well as a damper suitable for use in the pedal device.

What is claimed is:
 1. A pedal device for an automobile comprising: apedal arm, a damper for imparting a resistance force to the rotation ofsaid pedal arm, said damper including a movable member which is disposedmovably in an axial direction but immovable in a direction about theaxis, a rotating member disposed rotatably about the axis and facingsaid movable member, spring means for resiliently urging said movablemember toward said rotating member, and frictional-resistance-forcegenerating means for generating a frictional resistance force as theresistance force in the rotation of said rotating member, and forincreasing the frictional resistance force by increasing the springforce of said spring means by causing said movable member to move awayfrom said rotating member in the axial direction against the resiliencyof said spring means, and a rotatable shaft connected on one end thereofto said pedal arm and on another end thereof to said rotating member fortransmitting a rotation of said pedal arm to said rotating member, saiddamper having such an elastic deformation property with respect to saiddirection about the axis that the rotation of said pedal arm ispermitted from an initial position of rotation of said pedal arm to anyangle of 0.5 to 20% of a full angle of rotation thereof where saidrotating member is maintained in a stationary state by the frictionalresistance force of said damper, whereby a torque which graduallyincreases is imparted to said rotating member in said stationary statefrom said initial position to said angle, and that, when said pedal armis rotated more than said angle, the frictional resistance force isovercome by the increased torque of said rotating member, whereby saidrotating member is rotated in conjunction with the rotation of saidpedal arm.
 2. The pedal device for an automobile according to claim 1,wherein said frictional-resistance-force generating means has aninclined surface formed on one surface of said rotating member facingsaid movable member and an inclined surface formed on one surface ofsaid movable member facing said rotating member and adapted to bebrought into planar contact with said inclined surface.
 3. The pedaldevice for an automobile according to claim 1 or 2, wherein said movablemember has a movable member body and a projection formed integrally onone surface of said movable member body in such a manner as to projectin the axial direction toward one surface of said rotating member, saidrotating member has a rotating member body and a projection formedintegrally on one surface of said rotating member body in such a manneras to project in the axial direction toward the one surface of saidmovable member, and said frictional-resistance-force generating meanshas inclined surfaces which are formed on both projections of saidmovable member and said rotating member and are brought into planarcontact with each other.
 4. The pedal device for an automobile accordingto claim 1, further comprising a rotatable shaft for transmitting therotation of said pedal arm to said rotating member, said damper furtherincluding a hollow cylindrical member in which said movable member andsaid rotating member are accommodated and a cover disposed at one endsurface of said hollow cylindrical member in such a manner as to beimmovable in the direction about the axis, said rotating member being incontact with said cover in such a manner as to be slidable in thedirection about the axis and by being urged by the spring force of saidspring means, and said movable member being in contact with said hollowcylindrical member in such a manner as to be slidable in the axialdirection.
 5. The pedal device for an automobile according to claim 4,wherein said pedal arm and said rotatable shaft are substantially rigidmembers in comparison with said hollow cylindrical member, said rotatingmember, said movable member, and said cover, and the rotation of saidpedal arm from the initial position of rotation to any angle of 0.5 to20% of the full angle of rotation is permitted by the elasticdeformation of at least one of said hollow cylindrical member, saidrotating member, and said movable member.
 6. The pedal device for anautomobile according to claim 4 or 5, wherein a modulus of elasticity inbending, E, of a material for forming said hollow cylindrical member issuch that 2×10⁴ kgf/cm²≦E.
 7. The pedal device for an automobileaccording to claim 4 or 5, wherein the material for forming said hollowcylindrical member comprises a resin.
 8. The pedal device for anautomobile according to claim 7, wherein the material for forming saidhollow cylindrical member comprises one kind or two or more kindsselected from a polyamide resin, a polyoxymethylene resin, athermoplastic polyester resin, a liquid crystal polyester resin, amodified polyphenylene ether resin, a polyphenylene sulfide resin, apolyether sulfone resin, an aliphatic polyketone resin and a polyetherketone resin.
 9. The pedal device for an automobile according to claim7, wherein the material for forming said hollow cylindrical membercontains one kind or two or more kinds selected from graphite,fluororesin, molybdenum disulfide, boron nitride, glass fibers, carbonfibers, aromatic polyamide fibers and potassium titanate whiskers, aswell as lead, zinc, tin and copper and alloys thereof.
 10. The pedaldevice for an automobile according to claim 4, wherein the material forforming said hollow cylindrical member comprises a metal.
 11. The pedaldevice for an automobile according to claim 1, wherein a modulus ofelasticity in bending, E, of a material for forming said movable memberis such that 2×10⁴ kgf/cm²≦E≦20×10⁴ kgf/cm².
 12. The pedal device for anautomobile according to claim 1, wherein a modulus of elasticity inbending, E, of a material for forming said movable member is such that5×10⁴ kgf/cm²≦E≦20×10⁴ kgf/cm².
 13. The pedal device for an automobileaccording to claim 1, wherein a modulus of elasticity in bending, E, ofa material for forming said movable member is such that 7×10⁴kgf/cm²≦E≦18×10⁴ kgf/cm².
 14. The pedal device for an automobileaccording to claim 1, wherein a modulus of elasticity in bending, E, ofa material for forming said rotating member is such that 2.5×10⁴kgf/cm²≦E≦25×10⁴ kgf/cm².
 15. The pedal device for an automobileaccording to claim 1, wherein a modulus of elasticity in bending, E, ofa material for forming said rotating member is such that 5×10⁴kgf/cm²≦E≦23×10⁴ kgf/cm².
 16. The pedal device for an automobileaccording to claim 1, wherein a modulus of elasticity in bending, E, ofa material for forming said rotating member is such that 10×10⁴kgf/cm²≦E≦20×10⁴ kgf/cm².
 17. The pedal device for an automobileaccording to claim 1, wherein materials for forming said rotating memberand said movable member comprise resins.
 18. The pedal device for anautomobile according to claim 17, wherein each of materials for formingsaid rotating member and said movable member comprises one kind or twoor more kinds selected from a polyamide resin, a polyoxymethylene resin,a thermoplastic polyester resin, a liquid crystal polyester resin, amodified polyphenylene ether resin, a polyphenylene sulfide resin, apolyether sulfone resin, an aliphatic polyketone resin and a polyetherketone resin.
 19. The pedal device for an automobile according to claim17 or 18, wherein each of the materials for forming said rotating memberand said movable member contains one kind or two or more kinds selectedfrom graphite, fluororesin, molybdenum disulfide, boron nitride, glassfibers, carbon fibers, aromatic polyamide fibers and potassium titanatewhiskers, as well as lead, zinc, tin and copper and alloys thereof.